#pragma once 

#include<iostream>
#include<queue>
#include<pthread.h>

template<class T>
class BlockQueue
{
    static const int defaultnum = 20;
public:
    BlockQueue(int maxcap = defaultnum)
        :maxcap_(maxcap)
    {
        pthread_mutex_init(&mutex_, nullptr);
        pthread_cond_init(&c_cond_, nullptr);
        pthread_cond_init(&p_cond_,nullptr); 
    }

    T pop()
    {
        pthread_mutex_lock(&mutex_);
        while(q_.size() == 0)
        {
            pthread_cond_wait(&c_cond_, &mutex_); 
        }

        T out = q_.front();
        q_.pop();

        pthread_cond_signal(&p_cond_);
        pthread_mutex_unlock(&mutex_);

        return out; 
    }

    void push(const T &in)
    {
        pthread_mutex_lock(&mutex_);
        while(q_.size() == maxcap_)
        {
            pthread_cond_wait(&p_cond_, &mutex_); 
        }

        q_.push(in); 
        pthread_cond_signal(&c_cond_);
        pthread_mutex_unlock(&mutex_); 
    }

    ~BlockQueue()
    {
        pthread_mutex_destroy(&mutex_);
        pthread_cond_destroy(&c_cond_);
        pthread_cond_destroy(&p_cond_); 
    }
private:
    std::queue<T> q_;
    int maxcap_;
    pthread_mutex_t mutex_;
    pthread_cond_t c_cond_;
    pthread_cond_t p_cond_; 
};
